U.S. patent number 6,565,638 [Application Number 09/807,868] was granted by the patent office on 2003-05-20 for portable air-borne bacteria sampler.
This patent grant is currently assigned to Midori Anzen Co., Ltd.. Invention is credited to Yutaka Hatta, Yukihiro Nakata, Naoki Sugita, Takeshi Yamada.
United States Patent |
6,565,638 |
Sugita , et al. |
May 20, 2003 |
Portable air-borne bacteria sampler
Abstract
After supporting a petri dish S having a culture medium K
contained therein with a given thickness on a petri dish holder 17
of a housing 14, a nozzle holder 13 is clamped at a top of the
housing 14. When a motor 19 is energized to rotate a high static
pressure fan 18, air is introduced through nozzle openings 12a, and
flows through a space between the nozzle 15 and the culture medium
K. By setting a distance between the nozzle and the culture medium
to 0.5-1.5 mm, a high collection efficiency can be attained.
Inventors: |
Sugita; Naoki (Tokyo,
JP), Hatta; Yutaka (Tokyo, JP), Yamada;
Takeshi (Tokyo, JP), Nakata; Yukihiro (Tokyo,
JP) |
Assignee: |
Midori Anzen Co., Ltd. (Tokyo,
JP)
|
Family
ID: |
27469810 |
Appl.
No.: |
09/807,868 |
Filed: |
June 7, 2001 |
PCT
Filed: |
October 20, 1999 |
PCT No.: |
PCT/JP99/05784 |
PCT
Pub. No.: |
WO00/24865 |
PCT
Pub. Date: |
May 04, 2000 |
Foreign Application Priority Data
|
|
|
|
|
Oct 26, 1998 [JP] |
|
|
10-304067 |
Oct 26, 1998 [JP] |
|
|
10-304068 |
Apr 19, 1999 [JP] |
|
|
11-110302 |
Apr 19, 1999 [JP] |
|
|
11-110303 |
|
Current U.S.
Class: |
96/413; 73/28.05;
73/863.22 |
Current CPC
Class: |
G01N
1/2273 (20130101); G01N 1/2205 (20130101); G01N
2001/2276 (20130101) |
Current International
Class: |
C12M
1/26 (20060101); G01N 001/00 () |
Field of
Search: |
;96/413 ;55/320,418
;73/28.05,863.21,863.22 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Hopkins; Robert A.
Attorney, Agent or Firm: Varndell & Varndell, PLLC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a U.S. national phase application of
International Application No. PCT/JP99/05784 filed Oct. 20, 1999,
which application was not published in English.
Claims
What is claimed is:
1. A portable type airborne microorganism sampler comprising a
nozzle having a plurality of openings formed therein, a nozzle
holder supporting the nozzle, a petri dish holder arranged at a
downstream position of an air flow supporting a petri dish
containing a culture medium, and a fan generating the air flow, a
distance between a surface of the culture medium and the nozzle is
set to 0.5-1.5 mm, an air-flow velocity of the air flow through the
openings of the nozzle being set to be not lower than 20 m/
sec.
2. A portable type airborne microorganism sampler according to
claim 1, wherein said fan is a high static pressure fan having a
static pressure not lower than 400 Pa under a nominal air-flow
rate.
3. A portable type airborne microorganism sampler comprising a
nozzle having a plurality of openings formed therein, a nozzle
holder supporting the nozzle, a petri dish holder being arranged at
a downstream position of an air flow supporting a petri dish
containing a culture medium, a fan generating the air flow, a
distance between a surface of the culture medium and the nozzle
being set to 0.5-1.5 mm, an air-flow velocity of the air flow
through the openings of the nozzle being set to be not lower than
20 m/sec, and a filter is arranged at an exhaust port of the air
flow.
4. A portable type airborne microorganism sampler according to
claim 3, wherein said filter is formed by folding a sheet-like
filter member into a pleated form.
5. A portable type airborne microorganism sampler according to
claim 4, wherein the filter is formed in a circular shape.
6. A portable type airborne microorganism sampler comprising a
nozzle having a plurality of openings formed therein, a nozzle
holder supporting said nozzle, a petri dish holder arranged at a
downstream position of an air flow supporting a petri dish
containing a culture medium, and a fan generating the air flow,
characterized in that said openings of nozzle are arranged in a
grid-like manner.
7. A portable type airborne microorganism collecting sampler
according to claim 6, wherein said nozzle openings are arranged
with a pitch not smaller than 2.6 mm.
8. A portable type airborne microorganism collecting sampler
according to claim 6, wherein a total surface area of said nozzle
openings is set not smaller than 28.3 mm.sup.2.
Description
TECHNICAL FIELD
The present invention relates to a portable type airborne
microorganism sampler for collecting airborne microorganisms in a
room for monitoring and managing a pollution due to microorganisms
and bacteria and fungi.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective of the sampler;
FIG. 2 is a plan view thereof;
FIG. 3 is a cross sectional view thereof;
FIG. 4 is a side view of a nozzle;
FIG. 5 is a cross sectional view of an opening of the nozzle;
FIG. 6 is an actual and ideal impactor cutoff curves.
FIG. 7 is a graph representing a relationship between a culture
medium-nozzle distance and a collection efficiency;
FIG. 8 is a graph denoting a relationship between a air-flow
velocity through the nozzle and a collection efficiency;
FIG. 9 is a perspective view showing a radially pleated filter;
FIG. 10 is a perspective view illustrating a parallelly pleated
filter; and
FIG. 11 is a plan view showing a known sampler.
TECHNICAL BACKGROUND
There have been proposed a stationary type airborne microorganism
sampler and a portable type airborne microorganism sampler for
monitoring a condition of microorganism pollution by collecting
airborne microorganisms such as bacteria and fungi in
pharmaceutical factories and food factories and public spaces such
hospitals.
Particularly, a portable type light weight airborne microorganism
sampler has been used for managing and checking a pollution within
a space where a condition of microorganism pollution has to be
monitored and managed such as biological clean room and
manufacturing lines in the pharmaceutical factories and food
factories.
FIG. 11 is a plan view showing a known portable type sampler, which
is mainly consisting of a collecting section 1 and an operating
section 2. The operating section 2 has a handle 3 by means of which
a user can carry the sampler. At a front end of the collection
section 1, there is clamped a nozzle portion 4 through which an air
is introduced for collecting airborne microorganisms. The nozzle
portion 4 has a number of openings 5 arranged radially.
(1) In the known air sampler mentioned above, the stationary type
sampler has a sufficiently high collection efficiency, measured by
JIS method, because the measurement is carried out under the JIS
method, but it uses a large suction pump, and therefore it is
liable to be large in size and heavy in weight. Moreover, AC 100V
power supply is required as the main power, and therefore it is
difficult to conduct the measurement at any place.
Although the portable type air sampler can be small in size and
light in weight by using a small fan such as sirocco fan and radial
fan, a high static pressure could not be attained. Therefore, in
order to introduce a sufficiently large air-flow rate through the
nozzle portion 4, the nozzle openings have to be configured such
that the sampler can operate under a low static pressure, but this
makes a collection efficiency low. If the suction nozzle is
configured to have a high collection efficiency, a sufficiently
large air-flow rate could not be realized by a static pressure of
about 200 Pa which is obtained by the radial fan. Then, air-flow
velocity through the nozzle portion 4 becomes lower and a high
collection efficiency could not be attained.
(2) Furthermore, in the portable type airborne microorganism
sampler, use is made of a fan motor for generating an air flow for
collecting microorganisms, carbon particles are produced by a brush
portion of the motor and further droplets of a lubricant oil are
generated. In the known airborne microorganism sampler, these
particles and droplets are spread out of an exhaust port of the
sample together with an air flow and might contaminate a clean
room.
(3) Moreover, since the nozzle openings 5 are arranged radially,
the number of nozzle openings per unit surface area of the nozzle
portion 4 varies depending upon positions thereof. This results in
that a quantity of an air flow passing through the nozzle portion
per unit surface area thereof varies. In a place where a larger
air-flow rates, the culture medium is liable to be dried to
decrease a collection efficiency and even after the incubation, a
colony is hardly formed. In a place where a distance between
successive nozzle openings 5 is small, since collected
microorganisms come closer to each other and colonies might be
contacted with each other, and then the number of colonies could
not be counted accurately.
The present invention has for its object to provide a small and
light portable type airborne microorganism sampler, which can solve
the above mentioned problem (1), and has a high collection
efficiency.
It is another object of the invention to provide a small and light
portable type airborne microorganism sampler, which can solve the
above problem (2) and can collect airborne microorganisms
positively without contaminating a surrounding environment.
It is another object of the invention to provide a portable type
airborne sampler, which can solve the above mentioned problem (3),
can produce a uniform air flow through a nozzle portion per unit
surface area thereof, and can measure precisely the number and
positions of colonies produced after collection and
cultivation.
DISCLOSURE OF THE INVENTION
According to the invention, a portable type airborne microorganism
sampler comprises a nozzle having a plurality of openings formed
therein, a nozzle holder supporting said nozzle, a petri dish
holder arranged at a downstream position of an air flow supporting
a petri dish containing a culture medium, and a fan generating the
air flow, characterized in that a distance between a surface of the
culture medium and said nozzle is set to 0.5-1.5 mm.
According to further aspect of the invention, a portable type
airborne microorganism sampler comprises a nozzle having a
plurality of openings formed therein, a nozzle holder supporting
said nozzle, a petri dish holder arranged at a downstream position
of an air flow supporting a petri dish containing a culture medium,
and a fan generating the air flow, characterized in that an
air-flow velocity through the openings of nozzle is set to be not
lower than 20 m/sec.
According to further aspect of the invention, a portable type
airborne microorganism sampler comprises a nozzle having a
plurality of openings formed therein, a nozzle holder supporting
said nozzle, a petri dish holder arranged at a downstream position
of an air flow supporting a petri dish containing a culture medium,
and a fan generating the air flow, characterized in that said
openings of nozzle are arranged in a grid-like manner.
BEST MODE OF THE INVENTION
FIG. 1 is a perspective view showing the portable type airborne
microorganism sampler according to the invention, FIG. 2 is a plan
view thereof, and FIG. 3 is a cross sectional view thereof. The
portable type sampler is mainly composed of a collecting section 11
for collecting airborne microorganisms and an operating section 12.
The operating section 12 includes a grip 13 for carrying the
sampler. The collecting section 11 comprises a cylindrical housing
14 and a nozzle 15 having a number of fine nozzle openings 15a
formed therein, said nozzle being supported by a nozzle support 16
at a top of the housing 14 as illustrated in FIG. 4. The nozzle
openings 15a are arranged in a grid-like manner, and an opening is
formed by a straight tube portion 15b having a diameter of 0.36 mm
and a height of 0.5 mm and a tapered portion 15c having a open
angle of 90 degrees and a height of 0.5 mm as depicted in FIG. 5,
the taped portion serving to reduce a pressure loss in the nozzle
15.
In order to avoid an air leakage, the nozzle holder 16 is screwed
to the housing 14. A chalet holder 17 is provided immediately below
the nozzle 15, said chalet holder supporting a petri dish S which
contains a culture medium K. A distance d between the nozzle 15 and
the culture medium K is set to 0.5-1.5 mm. Within a space formed
underneath the petri dish holder 17, there are arranged a high
static pressure fan 18 such as turbofan and vortex blower, a motor
19 for driving the high static pressure fan 18 and a control
circuit, and an air-flow velocity not lower than 20 m/sec can be
attained. An exhaust filter 20 is arranged at a lowermost
position.
Upon operation, the petri dish S having the culture medium K
contained therein with a given thickness is supported by the petri
dish holder 17 in the housing 14, and then the nozzle holder 16 is
clamped at the top of the housing 14. When the motor 19 is driven
to rotate the high static pressure fan 18, an air is introduced
through the nozzle openings 15a and flows though a space between
the nozzle 15 and the culture medium K as illustrated in FIG. 5.
When the air-flow velocity through the nozzle 15 is set to be not
lower than 20 m/sec, the culture medium K serves as a collection
plate, and airborne microorganisms such as bacteria and fungi are
impacted against a surface of the culture medium K by inertia force
and are collected thereby. After that, the air stream is sucked by
the high static pressure fan 18 through a space formed in a
circumferential portion and is exhausted through the exhaust filter
20 as shown by arrows in FIG. 3.
Now it is assumed that bacillus subtilis having a particle size of
0.7 .mu.m are to be collected effectively. According to an ideal
graph representing a relationship between a limit particle size and
a collection efficiency shown in FIG. 6 (Aerosol Technology, page
114, FIG. 5.8, "Ideal and Practice of Limit Particle Size of
Impact", published on Apr. 10, 1985 from INOUE SHOIN Co. Ltd.
Japan), when it is desired to attain a collection efficiency not
lower than 50%; a Stokes number S.sub.tk is preferably set to be
not lower than 0.22 (S.sub.tk.sup.1/2 not lower than 0.47), when it
is desired to realize a collection efficiency not lower than 95%, a
Stokes number S.sub.tk is preferably set to be not lower than 0.3
(S.sub.tk.sup.1/2 not lower than 0.55). It should be noted that the
Stokes number S.sub.tk may be defined by the following equation,
wherein a particle density is .rho., a particle size is d, an
air-flow velocity U, Cunningham constant C, an air viscosity .eta.,
and a nozzle opening inner diameter D.
When the known portable type airborne microorganism sampler is
experimentally used to collect bacillus subtilis having a particle
size of 0.7 .mu.m, a collection efficiency of about 10% is obtained
under a condition that an air-flow velocity is 11.8 m/sec and a
nozzle opening diameter is 0.6 mm. From the equation (1), this
corresponds to a case in which a stokes number S.sub.tk is about
0.07 (S.sub.tk.sup.1/2 is about 0.27), and a sufficient collection
could not be carried out. In order to increase a collection
efficiency not less than 90% for bacillus subtilis, it is necessary
to increase the Stokes number S.sub.tk to 0.2-0.3 (S.sub.tk.sup.1/2
=0.45-0.55). In order to attain S.sub.tk= 0.3, from the equation
(1), an air-flow velocity should be increased to 48.4 m/sec which
is higher than the known value by about 4.1 times.
However, it has been generally known that a pressure loss is
increased in proportion to a square of an air-flow velocity, and
therefore since both pressure loss and an air-flow rate are
increased, a necessary workload is increased by 69 times.
Therefore, such a system could not be realized practically.
As expressed by the equation (1), the Stokes number S.sub.tk in
inversely proportional to an inner diameter of a nozzle opening,
the smaller a diameter of a nozzle opening is, the larger the
Stokes number S.sub.tk is obtained, and thus a collection
efficiency is increased. Therefore, a diameter of nozzle opening is
reduced from 0.6 mm to 0.36 mm, a necessary air-flow velocity for
increasing a collection efficiency for bacillus subtilis not less
than 90% can be reduced. This results in that a pressure loss is
decreased and a necessary electric power can be reduced. In order
to realize such a high static pressure, it is preferable to use a
turbofan having a static pressure not less than 400 Pa under a
nominal air-flow velocity.
The inventors have found experimentally that a collection
efficiency is affected not only by a Stokes number S.sub.tk, but
also by a distance between the culture medium and the nozzle. A
collection efficiency is mainly dependent upon this distance, and
when this distance is too short, a quantity of air is increased and
a collection efficiency is decreased, and when this distance is too
large, a velocity of particulate substances impacting upon the
culture medium is decreased and a collection efficiency is also
decreased. From experiments, it has been found that when a distance
between the culture medium and the nozzle is shorter than 1.5 mm, a
collection efficiency becomes not less than 90%, and when the
distance is longer than 1.6 mm, a collection efficiency becomes not
higher than 85% as shown in FIG. 7.
Therefore, according to the invention, a distance between the
culture medium and the nozzle is set to a value within a range of
0.5-1.5 mm. Then, it is possible to attain a higher collection
efficiency than the known portable type sampler, and this
efficiency is not less than that obtained by the known stationary
type sampler.
From the equation (1), in case of S.sub.tk =0.3, it is necessary to
increase a wind speed higher than the known value by about 4.1
times. However, by decreasing the number of nozzle openings 15a to
reduce a quantity of air by 4.1 times, a necessary electric power
can be reduced by 4.1 times. Even in such a case, a workload (W)
becomes larger than the original value by about 17 times. Since the
Stokes number S.sub.tk is inversely proportional to a diameter of a
nozzle opening, the smaller a diameter of a nozzle opening is, the
larger the Stokes number S.sub.tk is obtained, and thus a
collection efficiency is increased. Therefore, when a diameter of
nozzle opening is reduced from 0.6 mm to 0.36 mm, a necessary
air-flow velocity for increasing a collection efficiency for
bacillus subtilis having a particle size of 0.7 .mu.m not less than
90% can be reduced from 48.4 m/sec to 29.0 m/sec. When an air-flow
is decreased, a pressure loss is reduced, and thus a necessary
electric power can be decreased.
In the present embodiment, a relationship between an air-flow
velocity of an air stream passing through the nozzle portion and a
collection efficiency is experimentally represented by a graph
shown in FIG. 8. From this result, it is understood that in order
to obtain a collection efficiency not lower than 90%, an air-flow
velocity of about 23 m/sec is required, and a minimum collection
efficiency not lower than 50% is realized by an air-flow velocity
not lower than 20 m/sec.
In practice, a collection efficiency not lower than 50% is very
effective, but in the known portable type sampler, since use is
made of a radial fan, a high static pressure is not obtained and a
sufficiently high collection efficiency could not be attained.
Therefore, in the present embodiment, in order to realize an
air-flow velocity not lower than 20 m/sec, use is made of a
turbofan having a static pressure not lower than 400 Pa under a
nominal air-flow rate to solve the problem of low static pressure,
and a higher collection efficiency than the known portable type
sampler can be obtained. The portable type sampler according to the
invention has a comparative performance to the known stationary
type sampler.
Usually the sampler is used within a clean room, and thus it is
necessary to make an exhausted air from the sampler to be clean
substantially equal to or much cleaner than an atmosphere in the
clean room. To this end, the filter 20 for purifying the exhausted
air is provided at a downstream position with respect to the fan
motor 19 near the exhaust port. The filter 20 has a highly
purifying capability and may be preferably formed by a HEPA (High
Efficiency Particulate Air) filter made of glass fibers, which can
collect particles having a size of 0.3 .mu.m by not lower than
99.97%. If a further purification is required in order to reduce
the number of particles exhausted from the sampler, it is
preferable to use a ULPA (Ultra Low Penetration Air) filter which
is made of a glass and has a collection efficiency not lower than
99.999% for particles having a size of 0.1-0.2 .mu.m.
The filter 20 is formed by folding a filter sheet by a mini-pleat
treatment with a folded width not wider than 75 mm. In the portable
type sampler according to the invention, in order to loose an
advantage of small size and light weight, it is preferable to
reduce a thickness of the filter 20. Then, a pleat folding width is
preferably set to 15-50 mm, and in a practical sampler, a pleat
folding width is set to 25 mm. By using such a filter 20, a high
collection efficiency and low pressure loss can be maintained.
Dust particles or debris might leak from a space between the filter
20 and the housing, and therefore it is necessary to provide a
sufficient sealing around the filter, but in order to save a space,
the filter 20 is formed to have a central hole into which a part of
the motor 19 is projected. In this case, a filter supporting and
sealing frame 21 is detachably secured to the sampler main body in
order to prevent a leakage of the air stream at a downstream
position of the motor as shown in FIG. 3.
The filter 20 having the pleated portion as well as the above
mentioned central hole may preferably be formed in a circular shape
by pleating the filtering member 17a as shown in FIG. 9 or in a
circular shape by pleating the filtering member parallelly as shown
in FIG. 10, because the sampler main body has a tubular shape for
installing the circular petri dish.
In the radially pleated filter, a distance between successive
ridges in an inner area becomes different from a distance between
successive ridges in an outer area, and thus there is produced a
small unevenness in a pressure loss. The parallelly pleated filter
is superior to the radially pleated filter in this point. On the
other hand, the radially pleated filter can be manufactured much
more easily than the parallelly pleated filter. Therefore, either
one may be selected suitably by also considering the existence of
the central hole for escaping the motor.
In general, the portable type sampler is used under such a
condition that the electric power supply is limited. That is to
say, the portable type sampler is energized with a dry battery or
rechargeable battery. Therefore, the filter 20 might increase in a
pressure loss and a load of the motor 19 is increased. Then, a
power consumption (an air-flow velocity.times.a total sum of
pressure losses.times.a coefficient) might be increased. Therefore,
a usable time period is shortened and an operation time is reduced.
In order to obtain a same operation time, it is necessary to
provide a battery of a large capacity. Then, the sampler becomes
large in size and heavy in weight and the merits of the portable
type might be lost.
Accordingly, it is preferable that when the high static pressure
fan 18 having a static pressure under a nominal air-flow rate is
used under an air-flow velocity of not lower than 20 m/sec passing
through the nozzle openings, the filter 20 is constructed such that
a static pressure becomes not higher than 10%, more preferably 8%
of the static pressure of the high static pressure fan 18 under a
nominal quantity of the air flow. In the present embodiment, the
filter is set such that the static pressure becomes 100 Pa which is
equal to 10% of a static pressure of about 1000 Pa of the high
static pressure fan 18 under a nominal quantity of the air flow.
Then, an increase in the power consumption can be limited to about
10%. In an actual use, a negligible reduction in an operating time,
i.e. measuring period could be attained. In this manner, although
the transitivity is reduced by the filter 20, the exhausted air can
be purified sufficiently without decreasing an operation time.
In the present embodiment, the nozzle openings 15a are aligned
regularly with a pitch of 2.6 mm along the up and down direction as
well as along the right and left direction, i.e. in a square
grid-like manner. Therefore, after incubation, colonies are also
formed regularly along the nozzle openings 15a, and the colonies
can be counted easily without fail without using a special method
or special colony counting device. Then, the colony counting can be
easily carried out by inexperienced persons with a substantially
same level as experienced persons.
The number of the nozzle openings 15a is preferably set such that a
total surface area of the nozzle openings is not smaller than 28.3
mm.sup.2. This total surface area of 28.3 mm.sup.2 of the nozzle
openings may be calculated from an air-flow rate passing through
the nozzle 15 per unit time such that an air-flow velocity at the
nozzle 15 becomes 20 m/sec can be obtained.
Since the nozzle 15 has the openings 15a such that a total surface
area of the openings is 28.3 mm.sup.2, an air-flow velocity passing
through the nozzle 15 becomes not lower than 20 m/sec, and the
culture medium K effectively serves as a collection plate, and
microorganisms such as bacteria and fungi can be impacted by
inertia force upon the surface of the culture medium K and can be
collected effectively.
When the nozzle openings are arranged radially like as the known
sampler shown in FIG. 11, the number of nozzle openings varies
depending upon positions on the nozzle 15, and the number of nozzle
openings per unit surface area varies. Therefore, an air-flow rate
passing through unit surface area of the nozzle differs for
respective positions of the nozzle. Then, an air-flow rate
projected onto the culture medium K becomes non-uniform and the
culture medium might be dried locally and a collection efficiency
is liable to be lower at a dried area and a colony is hardly
produced even if microorganisms are collected thereon.
In the present embodiment, by arranging the nozzle openings 15a
regularly in a square grid-like manner, a quantity of wind per unit
surface area of the nozzle 15 can be uniform over the whole
surface, and thus the air is projected uniformly up to the surface
of the culture medium K in the petri dish S. In this manner, the
above problem can be solved.
Furthermore, in order to check or judge collected microorganisms,
colonies are formed by culturing the collected microorganisms for
more than 24 hours. The inventors have found that a size of
colonies is not larger than about 2.5 mm, and therefore the
colonies can be formed separately from each other and can be
counted when a pitch of the nozzle openings 15a is set not less
than 2.6 mm. Moreover, in the known radially arranged nozzle, it is
impossible to define a nozzle opening through which a microorganism
has passed, and thus it could not be judged whether a colony is not
formed even if a microorganism has been collected or because
microorganism is shielded by the nozzle. However, in the present
embodiment, since the nozzle openings 15a are arranged in a square
grid-like manner, a position can be easily determined and the
calculation can be performed smoothly.
APPLICABILITY IN THE INDUSTRIAL FIELD
As explained above, in the portable type airborne microorganism
collecting sampler according to the invention, by setting a
distance between the nozzle and the surface of the culture medium
to 0.5-1.5 mm, although the sampler is a small and light portable
type one, the sampler can be used with a high collection efficiency
for a long time, and can be cheap and can have a high
performance.
Furthermore, by setting an air-flow velocity flowing through the
nozzle having a plurality of openings formed therein to not less
than 20 m/sec, although the sampler is a small and light portable
type, the sampler can be used with a high collection efficiency for
a long time, can be cheap in price, can be safe and can be easily
handled.
Moreover, by arranging a filter at the exhaust port, the exhausted
air can be free from dusts and debris, and a contamination of a
clean room can be avoided.
Since the nozzle openings of the nozzle for introducing an air for
collecting airborne microorganisms are arranged regularly in a
grid-like manner, a uniform quantity of air can be projected upon
the culture medium in the petri dish, the culture medium can be
prevented from being locally dried to decrease a collection
efficiency and to form colonies, colonies can be effectively
prevented from being contacted with each other after culturing to
make the colony count impossible. Therefore, positions and counts
of collected microorganisms can be accurately measured.
* * * * *